Frame structure for control signaling instances

ABSTRACT

A method, an apparatus, and a computer program for wireless communication that allows for greater scheduling flexibility of physical resources are disclosed. A UE determines a time division duplex (TDD) frame structure for a plurality of frames, where the plurality of frames include a plurality of uplink (UL) subframes and a plurality of downlink (DL) subframes. The UE determines whether a control signaling instance is scheduled during an UL subframe of the plurality of UL subframes, wherein the control signaling instance is scheduled periodically and the control signaling includes at least one of a random access channel, an uplink control channel, a sounding reference signal (SRS), or a scheduling request (SR). The UE communicates the control signaling instance if the control signaling instance is scheduled during an UL subframe.

CROSS-REFERENCE TO RELATED APPLICATIONS(S)

This application is a divisional of U.S. patent application Ser. No.15/991,829, entitled “FRAME STRUCTURE DEPENDENT CONFIGURATION OFPHYSICAL CHANNELS” and filed May 29, 2018, which claims the benefit ofU.S. Provisional Patent Application Ser. No. 62/531,837, entitled “FRAMESTRUCTURE DEPENDENT CONFIGURATION OF PHYSICAL CHANNELS” and filed onJul. 12, 2017, which is expressly incorporated by reference herein inits entirety.

BACKGROUND Field

The present disclosure relates generally to communication systems, andmore particularly, to the allocation of physical downlink and uplinkresources.

Background

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. Some aspects of 5G NR may be based on the 4G Long TermEvolution (LTE) standard. There exists a need for further improvementsin 5G NR technology. These improvements may also be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

In telecommunication standards, such as LTE and 5G NR, wirelesscommunication systems allocate physical resources to establishcommunication links that allow for telecommunication services to beprovided to user equipment (UE) with a base station. Therefore, there isa need for systems and techniques that improve the efficiency andincrease the flexibility in which wireless communication systemsallocate physical resources.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

Transmissions between user equipment and base stations in a wirelesscommunication system are generally organized into frames, which arethemselves organized into sets of subframes (as further detailed below).A time division duplex (TDD) frame structure can be provided whichdesignates subframes as either downlink (DL) subframes (in which a basestation transmits information to the UE) or uplink (UL) subframes (inwhich a UE transmits information to the base station). While framestructures in some telecommunication standards (e.g., LTE) are staticwith regards to the assignment of subframes as either DL or UL, othertelecommunication standards are more dynamic in that subframes for datacan be designated as either DL or UL. However, with respect to theallocation of physical (PHY) layer resources related to synchronization,control, system information, and other non-data information, there maynot be much flexibility.

In LTE, frame structures allocate physical resources for UL and DL atfixed subframe positions. For example, the configuration of PHY layer ULresources for physical random access channel (PRACH), physical uplinkcontrol channel (PUCCH), sounding reference signals (SRS), or schedulingrequest (SR) resources is a function of the frame structure and is fixedonce the choice of frame structure is made. Other telecommunicationstandards (e.g., LTE enhanced Interference Mitigation and TrafficAdaptation (eIMTA)) may allow the frame structure to change dynamically,but a common set of resources across different configurations may stillbe required for PRACH, PUCCH, etc. In LTE Licensed Assisted Access(LAA), while the frame structure may be dynamic and the location ofresources may change with the frame structure, the resourceconfiguration for PUCCH may be fixed to certain types of subframe. Othersystems such as enhanced Machine Type Communication (eMTC or LTE-M),Narrowband IoT (NB-IoT), and Listen Before Talk (LBT) have more flexibleframe structures but may still require a minimum number of guaranteed DLsubframes and minimum number of guaranteed UL subframes in whichphysical DL resources and physical uplink resources for non-datatransmissions must be provided. The use of guaranteed DL and ULsubframes limits scheduling flexibility for physical resources sinceonly these subframes can be used for non-data transmissions. The use ofguaranteed DL and UL subframes also make it more difficult to allocatephysical resources when theses physical resources are shared amongvarious UEs since the assignment of physical downlink control channel(PDCCH), PUCCH, and other non-data information for the various UEs arelimited to the guaranteed DL and UL subframes.

This disclosure describes systems and techniques in which physicalresources for non-data information are allocated in a flexible mannerinto subframes as a function of a TDD frame structure. In this manner,the number of DL subframes and UL subframes in a set of frames may beflexibly assigned. Physical resources for non-data information may beassigned to any of the DL subframes (for physical DL resources) or ULsubframes (for physical UL resources) available rather than beingrestricted to a limited set of guaranteed DL or UL subframes. A UE mayreceive information about the frame structure of the set of frames froma base station to determine the size and location of DL subframes and ULsubframes. The systems and techniques also make it easier to allocateshared physical resources since physical resources can be distributedwithin a greater range of subframes within the frames.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus for wireless communication are provided in whichinformation is received by a UE from a base station. The receivedinformation indicates a TDD frame structure of a plurality of frames.The plurality of frames includes a plurality of subframes. The UE maydetermine a control channel search space within the plurality ofsubframes based on the received information about the TDD framestructure of the plurality of frames. The UE may also determine a searchstrategy including a maximum aggregation level based on the controlchannel search space. The UE may perform a blind decoding of the controlchannel search space with the search strategy to obtain controlinformation.

In another aspect of the disclosure, a method, a computer-readablemedium, and an apparatus for wireless communication are provided inwhich a UE determines a TDD frame structure of a plurality of frames. Aplurality of UL subframes of the plurality of frames assigned fortransmitting UL resources associated with a control signaling is afunction of the TDD frame structure. The UE may determine a location ofa scheduled UL resource within the TDD frame structure for communicatingone of a number of types of the control signaling. The type of controlsignaling includes at least one of PRACH, PUCCH, SRS, or SR. The UE maydetermine if the location of the scheduled UL resource for communicatinga type of the control signaling occurs on one of the plurality of ULsubframes assigned for transmitting the scheduled UL resource. If it is,the UE may communicate the type of the control signaling using thescheduled UL resource over one of the plurality of UL subframes.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a DLframe structure, DL channels within the DL frame structure, an UL framestructure, and UL channels within the UL frame structure, respectively.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIG. 4 illustrates different TDD frame structures for a set of subframesof a set of frames.

FIG. 5 illustrates PDCCH search spaces that are blind decoded based on anumber of DL subframes and a maximum aggregation level.

FIG. 6 illustrates PDCCH search spaces that are blind decoded based on adetermined subset of blind decodes.

FIG. 7 . illustrates different TDD frame structures with differentnumbers of UL subframes for assigning physical UL resources.

FIG. 8 illustrates a call flow diagram between a UE and a base station.

FIG. 9 illustrates a flow chart where a UE obtains control informationfrom a PDCCH search space.

FIG. 10 illustrates a flow chart where a UE communicates on physical ULchannels.

FIG. 11 a conceptual data flow diagram illustrating the data flowbetween different modules/means/components in an exemplary apparatus.

FIG. 12 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, and an Evolved Packet Core (EPC) 160. The basestations 102 may include macro cells (high power cellular base station)and/or small cells (low power cellular base station). The macro cellsinclude base stations. The small cells include femtocells, picocells,and microcells.

The base stations 102 (collectively referred to as Evolved UniversalMobile Telecommunications System (UMTS) Terrestrial Radio Access Network(E-UTRAN)) interface with the EPC 160 through backhaul links 132 (e.g.,S1 interface). In addition to other functions, the base stations 102 mayperform one or more of the following functions: transfer of user data,radio channel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160) with eachother over backhaul links 134 (e.g., X2 interface). The backhaul links134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacro cells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100 MHz) bandwidthper carrier allocated in a carrier aggregation of up to a total of YxMHz (x component carriers) used for transmission in each direction. Thecarriers may or may not be adjacent to each other. Allocation ofcarriers may be asymmetric with respect to DL and UL (e.g., more or lesscarriers may be allocated for DL than for UL). The component carriersmay include a primary component carrier and one or more secondarycomponent carriers. A primary component carrier may be referred to as aprimary cell (PCell) and a secondary component carrier may be referredto as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 192. The D2D communication link 192 may use theDL/UL WWAN spectrum. The D2D communication link 192 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, FlashLinQ, WiMedia,Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

The gNodeB (gNB) 180 may operate in millimeter wave (mmW) frequenciesand/or near mmW frequencies in communication with the UE 104. When thegNB 180 operates in mmW or near mmW frequencies, the gNB 180 may bereferred to as an mmW base station. Extremely high frequency (EHF) ispart of the RF in the electromagnetic spectrum. EHF has a range of 30GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters.Radio waves in the band may be referred to as a millimeter wave. NearmmW may extend down to a frequency of 3 GHz with a wavelength of 100millimeters. The super high frequency (SHF) band extends between 3 GHzand 30 GHz, also referred to as centimeter wave. Communications usingthe mmW/near mmW radio frequency band has extremely high path loss and ashort range. The mmW base station 180 may utilize beamforming 184 withthe UE 104 to compensate for the extremely high path loss and shortrange.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS Bearer Services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSGateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The base station may also be referred to as a gNB, Node B, evolved NodeB (eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), or some other suitableterminology. The base station 102 provides an access point to the EPC160 for a UE 104. Examples of UEs 104 include a cellular phone, a smartphone, a session initiation protocol (SIP) phone, a laptop, a personaldigital assistant (PDA), a satellite radio, a global positioning system,a multimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, a smart device, a wearabledevice, a vehicle, an electric meter, a gas pump, a toaster, or anyother similar functioning device. Some of the UEs 104 may be referred toas IoT devices (e.g., parking meter, gas pump, toaster, vehicles, etc.).The UE 104 may also be referred to as a station, a mobile station, asubscriber station, a mobile unit, a subscriber unit, a wireless unit, aremote unit, a mobile device, a wireless device, a wirelesscommunications device, a remote device, a mobile subscriber station, anaccess terminal, a mobile terminal, a wireless terminal, a remoteterminal, a handset, a user agent, a mobile client, a client, or someother suitable terminology.

In LTE, the allocation of physical resources (e.g., PRACH, PUCCH, SRS,SR) are fixed once the TDD frame structure is finalized. Thus, physicalresources are always maintained in particular subframe temporalpositions in LTE. With regards to LTE eIMTA and LAA, the TDD framestructure can change dynamically. Nevertheless, a least common set ofresources is defined in eIMTA for the allocation of physical resources(e.g., ePRACH, PUCCH, SRS, SR) across different frame configurations. InLTE LAA, the TDD frame structure can change dynamically and floats intime, however certain physical resources have fixed configurations. Forexample, a short PUCCH (sPUCCH) configuration may be fixed in LTE LAAbut allowed to float temporally. However, even in this case, the sPUCCHlocation starts and ends in subframes subject to a transmit opportunity(TxOP) time limit.

For eMTC-Uplink (eMTC-U) and NB-IoT-Uplink (NB-IoT-U), there has beensome discussion of having a dynamic type TDD frame structure with aself-contained transmission framework. Nevertheless, the DL-ULtransaction in eMTC-Uplink (eMTC-U) and NB-IoT-Uplink (NB-IoT-U) arecompleted within a TxOP (or a few TxOPs) and the DL transaction isalways within one TxOP. As such, TDD frame structures have previouslydefined minimum guaranteed DL subframes for the allocation of physicalDL resources and minimum guaranteed UL subframes for the allocationphysical UL resources.

In this disclosure however, frame structure dependent resourceconfigurations are disclosed that enable a higher scheduling flexibilityat a minimal increase in configuration complexity. These solutions evenlead to UE power savings depending on configuration settings.

Referring again to FIG. 1 , in certain aspects (see element 198), the UE104 may be configured to receive information from the base station 180.In the DL, the base station 180 may provide header compression,ciphering, packet segmentation and reordering, multiplexing betweenlogical and transport channels, and radio resource allocations to theUE. In this example, the information may indicate at least one of alocation or a size of a PDCCH search space within a set of subframes ofa set of frames. The location and/or the size of the PDCCH search spaceis a function of a TDD frame structure of the set of frames. In oneaspect, the information may indicate the structure of the TDD frames inthe set of frames. The UE may use this information to determine thelocation and size of a PDCCH search space within a set of subframes ofthe set of frames. For example, the information may indicate the numberof DL frames or the number of DL subframes in the set of frames. Basedon this information, the UE may determine the location and size of thePDCCH search space within the DL subframes in the set of frames.

For instance, the information may be broadcast in a physical DL channel,such as the physical broadcast channel (PBCH), and be provided asinformation within a master information block (MIB) or a systeminformation block (SIB). The control information for the UE 104, such asa common PDCCH or a UE specific PDCCH, may be within a set of DLsubframes in the set of frames. The UE 104 may perform a blind search tofind its control information in the DL subframes that make up the PDCCHsearch space.

As such, the UE 104 determines the PDCCH search space within the set ofDL subframes based on the received information indicating the locationand/or the size of the PDCCH search space or based on the receivedinformation indicating the structure of the TDD frames in the set offrames. To obtain the control information for the UE 104, the UE 104 mayperform a blind decoding or blind search of the determined PDCCH searchspace to obtain the control information. In one example, the UE 104 maydecode PDCCH candidates in the PDCCH search space until the UE 104 findsa common PDCCH or a UE specific PDCCH. The UE 104 may obtain the controlinformation from the common PDCCH or the UE specific PDCCH to obtaincontrol information which may include, for example, informationregarding physical UL resource allocations.

In another aspect of the disclosure, the UE 104 may be configured todetermine a TDD frame structure. The UE 104 may use the TDD framestructure to determine UL resources for the transmission of non-datainformation. For example, the UE 104 may receive information on the TDDframe structure on the common PDCCH or UE specific PDCCH. In one aspect,the UE 104 may receive information on the TDD frame structure throughthe PBCH, the MIB, or the SIB. The UE 104 may then use the informationabout the TDD frame structure to determine various physical resourcesavailable within UL subframes in the set of frames. For example, the UE104 may receive information indicating the number of DL frames, thenumber of DL subframes, the number of UL frames, or the number of ULsubframes in the set of frames. Based on this information, the UE 104may determine the location and size of the UL subframes in the set offrames. In this manner, the UE 104 may determine a location of at leastone of a PRACH, a PUCCH, SRS, or SR resources based on the determinedTDD frame structure. The UE 104 may then transmit at least one of thePRACH, the PUCCH, the SRS, the SR resources, or the measurements of apositioning reference signal (PRS) based on the determined location forthe at least one of the PRACH, the PUCCH, the SRS, or the SR resources.

In yet another aspect of the disclosure, the UE 104 may be configured todetermine a TDD frame structure. The UE 104 may use the TDD framestructure to determine DL resources for the measurement of channelquality and UL resources for the transmission of measurement of thechannel quality. For example, the UE 104 may receive information on theTDD frame structure through the common PDCCH or UE specific PDCCH. Inone aspect, the UE 104 may receive information on the TDD framestructure through the PBCH, the MIB, or the SIB. The UE 104 may then usethe information about the TDD frame structure to determine the locationand size of DL subframes and UL subframes in the set of frames. The UE104 is then configured to determine a number of the DL subframes overwhich to measure, and to average, a channel quality based on thedetermined TDD frame structure, and to send, over a number of the ULsubframes, a channel quality indicator (CQI) measured over thedetermined number of subframes.

FIG. 2A is a diagram 200 illustrating an example of a DL framestructure. FIG. 2B is a diagram 230 illustrating an example of channelswithin the DL frame structure. FIG. 2C is a diagram 250 illustrating anexample of an UL frame structure. FIG. 2D is a diagram 280 illustratingan example of channels within the UL frame structure. Other wirelesscommunication technologies may have a different frame structure and/ordifferent channels. A frame (10 ms) may be divided into 10 equally sizedsubframes. Each subframe may include two consecutive time slots. Aresource grid may be used to represent the two time slots, each timeslot including one or more time concurrent resource blocks (RBs) (alsoreferred to as physical RBs (PRBs)). The resource grid is divided intomultiple resource elements (REs). For a normal cyclic prefix, an RB maycontain 12 consecutive subcarriers in the frequency domain and 7consecutive symbols (for DL, OFDM symbols; for UL, SC-FDMA symbols) inthe time domain, for a total of 84 REs. For an extended cyclic prefix,an RB may contain 12 consecutive subcarriers in the frequency domain and6 consecutive symbols in the time domain, for a total of 72 REs. Thenumber of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry DL reference (pilot)signals (DL-RS) for channel estimation at the UE. The DL-RS may includecell-specific reference signals (CRS) (also sometimes called common RS),UE-specific reference signals (UE-RS), and channel state informationreference signals (CSI-RS). FIG. 2A illustrates CRS for antenna ports 0,1, 2, and 3 (indicated as R₀, R₁, R₂, and R₃, respectively), UE-RS forantenna port 5 (indicated as R₅), and CSI-RS for antenna port 15(indicated as R).

FIG. 2B illustrates an example of various channels within a DL subframeof a frame. The physical control format indicator channel (PCFICH) iswithin symbol 0 of slot 0, and carries a control format indicator (CFI)that indicates whether the physical downlink control channel (PDCCH)occupies 1, 2, or 3 symbols (FIG. 2B illustrates a PDCCH that occupies 3symbols). The PDCCH occupies the 1, 2, or 3 symbols at the beginning ofeach subframe as indicated by the PCFICH. The PDCCH carries downlinkcontrol information (DCI) within one or more control channel elements(CCEs), each CCE including nine RE groups (REGs) distributed across thefirst 1, 2, or 3 symbols of each subframe, each REG including fourconsecutive REs in an OFDM symbol. The number of CCEs in a PDCCH iscalled an aggregation level, and may be 1, 2, 4, 8, or 16 consecutiveCCEs. For example, a PDCCH with an aggregation level of 8 may use a CCEat the first 1, 2, or 3 symbols of each of 8 consecutive subframes. APDCCH with an aggregation level of n may only start on a boundary ofevery n subframes. For example, in the example of the PDCCH with anaggregation level of 8, the PDCCH may only start on subframe 0, 8, 16,etc. A UE may be configured with a UE-specific enhanced PDCCH (ePDCCH)that also carries DCI. The ePDCCH may have 2, 4, or 8 RB pairs (FIG. 2Bshows two RB pairs, each subset including one RB pair). The physicalhybrid automatic repeat request (ARQ) (HARQ) indicator channel (PHICH)is also within symbol 0 of slot 0 and carries the HARQ indicator (HI)that indicates HARQ acknowledgement (ACK)/negative ACK (NACK) feedbackbased on the physical uplink shared channel (PUSCH).

The primary synchronization channel (PSCH) may be within symbol 6 ofslot 0 within subframes 0 and 5 of a frame. The PSCH carries a primarysynchronization signal (PSS) that is used by a UE 104 to determinesubframe/symbol timing and a physical layer identity. The secondarysynchronization channel (SSCH) may be within symbol 5 of slot 0 withinsubframes 0 and 5 of a frame. The SSCH carries a secondarysynchronization signal (SSS) that is used by a UE to determine aphysical layer cell identity group number and radio frame timing. Basedon the physical layer identity and the physical layer cell identitygroup number, the UE can determine a physical cell identifier (PCI).Based on the PCI, the UE can determine the locations of theaforementioned DL-RS. The physical broadcast channel (PBCH), whichcarries a master information block (MIB), may be logically grouped withthe PSCH and SSCH to form a synchronization signal (SS) block. The MIBprovides a number of RBs in the DL system bandwidth, a PHICHconfiguration, and a system frame number (SFN). The physical downlinkshared channel (PDSCH) carries user data, broadcast system informationnot transmitted through the PBCH such as system information blocks(SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry demodulation referencesignals (DM-RS) for channel estimation at the base station. The UE mayadditionally transmit sounding reference signals (SRS) in the lastsymbol of a subframe. The SRS may have a comb structure, and a UE maytransmit SRS on one of the combs. The SRS may be used by a base stationfor channel quality estimation to enable frequency-dependent schedulingon the UL.

FIG. 2D illustrates an example of various channels within an UL subframeof a frame. A physical random access channel (PRACH) may be within oneor more subframes within a frame based on the PRACH configuration. ThePRACH may include six consecutive RB pairs within a subframe. The PRACHallows the UE to perform initial system access and achieve ULsynchronization. A physical uplink control channel (PUCCH) may belocated on edges of the UL system bandwidth. The PUCCH carries uplinkcontrol information (UCI), such as scheduling requests, a CQI, aprecoding matrix indicator (PMI), a rank indicator (RI), and HARQACK/NACK feedback. The PUSCH carries data, and may additionally be usedto carry a buffer status report (BSR), a power headroom report (PHR),and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a packet dataconvergence protocol (PDCP) layer, a radio link control (RLC) layer, anda medium access control (MAC) layer. The controller/processor 375provides RRC layer functionality associated with broadcasting of systeminformation (e.g., MIB, SIBs), RRC connection control (e.g., RRCconnection paging, RRC connection establishment, RRC connectionmodification, and RRC connection release), inter radio access technology(RAT) mobility, and measurement configuration for UE measurementreporting; PDCP layer functionality associated with headercompression/decompression, security (ciphering, deciphering, integrityprotection, integrity verification), and handover support functions; RLClayer functionality associated with the transfer of upper layer packetdata units (PDUs), error correction through ARQ, concatenation,segmentation, and reassembly of RLC service data units (SDUs),re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto transport blocks(TBs), demultiplexing of MAC SDUs from TBs, scheduling informationreporting, error correction through HARQ, priority handling, and logicalchannel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the DL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

FIG. 4 is a generalized representation of frame structures 400A-400D fora set of frames. In this example, a temporal duration of each of the TDDframe structures 400A-400D is 80 ms where each TDD frame structure400A-400D represents a set of frames. Therefore, there are 8 frames ineach of the TDD frame structures 400A-400D shown in FIG. 4 .Furthermore, in this example, each of the TDD frame structures 400A-400Dincludes LBT frames structures. Thus, the UE 104 begins each of the setof frames by performing a CCA or an enhanced CCA (ECCA), which has atemporal duration of approximately 3 ms. The UE 104 is then configuredto listen for a transmission signature from the base station 180 duringthe next 2 ms. The UE 104 uses the transmission signature to detecttransmission of the set of frames with one of the TDD frame structures400A-400D.

Each of the TDD frame structures 400A-400D then has a minimum guaranteedset of subframes 402 for DL. The minimum guaranteed set of subframes 402for DL may be used for a DL reference signal (DRS), radio resourcemanagement (RRM), and common control signals. The minimum guaranteed setof subframes 402 for DL may include at least one common PDCCH candidateand/or one UE specific PDCCH candidate for UEs with the highest coverageextension. However, as explained below, PDCCH candidates may also beallocated by the TDD frame structures 400A-400D to other subframes inthe set of frames.

Additionally, each of the TDD frame structures 400A-400D may alsoinclude a minimum guaranteed set of subframes 404 for UL in the lastframe of the set of frames. The minimum guaranteed set of subframes 404for UL may have a temporal duration of 10 ms, or one frame. The set ofsubframes 404 in the last frame with the TDD frame structures 400A-400Dmay be utilized to provide physical UL resources such as the PUCCH,PRACH, ePRACH, ACK/NACK feedback, P-CSI (periodic channel stateinformation), SRS, SR, etc.

However, as shown in FIG. 4 , one of the problems with providingphysical UL resources over the minimum guaranteed set of subframes 404for the UL in the last frame of the set of frames is when there aremultiple UEs that require physical UL resource allocations. For example,when a first UE uses the physical UL resources over the first 5 ms ofthe last frame to transmit, a second UE may not transmit. Conversely,when the second UE uses the physical UL resources over the final 5 ms ofthe last frame to transmit, the first UE may not transmit.

As such, to provide a frame structure with enhanced schedulingflexibility, the TDD frame structures 400A-400D may have differentflexible sections 406A, 406B, 406C, 406D with different portions forassigning physical resources for the DL and for the UL. The allocationof the physical resources of the frame structures 400A-400D between theDL and UL may depend on the physical resources needed for transmissionbetween the UE 104 and the base station 180. Each of the flexiblesections 406A, 406B, 406C, 406D is provided between the minimumguaranteed set of subframes 402 for the DL and the minimum guaranteedset of subframes 404 for the UL in the last frame of the set of frames.

In the TDD frame structure 400A containing the flexible section 406A,the entire flexible section 406A is used for physical DL resourcesexcept for a small gap at the end of the flexible section 406A that isutilized as a UL/gap. As such, a subset of the subframes of the set offrames within the flexible section 406A may be used to provide PDCCHsand PDSCHs. Thus, a PDCCH search space may extend beyond the minimumguaranteed set of subframes 402 for DL into the entire flexible section406A except for the UL/gap.

In the TDD frame structure 400B containing the flexible section 406B,the flexible section 406B includes a portion 408 for physical DLresources and a portion 410 that may be used for physical UL resources.As such, a subset of the subframes of the set of frames within theportion 408 may be used to provide PDCCHs and PDSCHs. In this example,the portion 410 includes the last frame in the frames within theflexible section 406B. Thus, the portion 410 may be used to providephysical UL resources such as the PUCCH, PRACH, ePRACH, ACK/NACKfeedback, P-CSI, SRS, SR in addition to the minimum guaranteed set ofsubframes 404 for the UL.

In the TDD frame structure 400C containing the flexible section 406C,the flexible section 406C includes a portion 412 for physical DLresources and a portion 414 that may be used for physical UL resources.As such, a subset of the subframes of the set of frames within theportion 412 may be used to provide PDCCHs and PDSCHs. In this example,the portion 414 includes the last three frames in the frames within theflexible section 406C. Thus, the portion 414 may be used to providephysical UL resources such as the PUCCH, PRACH, ePRACH, ACK/NACKfeedback, P-CSI, SRS, SR in addition to the minimum guaranteed set ofsubframes 404 for the UL.

In the TDD frame structure 400D containing the flexible section 406D,the entire flexible section 406D is used for physical UL resources.Thus, all five subframes within the flexible portion 406D are used forphysical UL resources Thus, the entire flexible section 406D may be usedto provide physical UL resources such as the PUCCH, PRACH, ePRACH,ACK/NACK feedback, P-CSI, SRS, SR in addition to the minimum guaranteedset of subframes 404 for the UL.

FIG. 5 illustrates a pair of PDCCH search spaces 500, 502. The PDCCHsearch spaces 500, 502 are provided by different TDD frame structures,such as the TDD frame structures 400A-400D shown in FIG. 4 . In thisexample, the PDCCH search space 500 has a maximum number of subframesthat may contain PDCCH candidates for the UE 104 to search. For example,the PDCCH search space 500 may be provided by the TDD frame structure400A in FIG. 4 with the flexible portion 406A. In this case the PDCCHsearch space 500 has a total number of 16 subframes, which may be thefirst 16 DL subframes in, or may be distributed through, the set offrames in a TDD frame structure.

With regard to the PDCCH search space 502, the PDCCH search space 502has less than the maximum number of subframes in the search space 500,and may contain PDCCH candidates for the UE to search. In this example,the PDCCH search space 502 may be provided by the TDD frame structure400B in FIG. 4 with the flexible portion 406B. The PDCCH search space502 has a total number of 8 subframes, which may be the first 8 DLsubframes in, or may be distributed through, the set of frames in a TDDframe structure.

Both of the PDCCH search spaces 500, 502 may be a function of the TDDframe structures. In particular, the number of PDCCH candidates in thePDCCH search spaces 500, 502 may be a function of the TDD framestructure. As explained above with regards to FIG. 1 , the informationfrom the base station 180 to the UE 104 may indicate at least one of alocation or a size of a PDCCH search space within a set of subframes ofa set of frames. The location and/or the size of the PDCCH search spaceare a function of the TDD frame structure of the set of frames. In oneaspect, the UE 104 may determine the location and/or the size of a PDCCHsearch size from information on the TDD frame structure received fromthe base station 180.

For example, with regards to the TDD frame structure 400A having theflexible section 406A, the base station 180 may indicate that the numberof DL subframes in the set of frames for the PDCCH search space 500 is16 DL subframes. As such, the UE 104 may receive information from thebase station 180 indicating the size of the PDCCH search space 500. Inone aspect, the UE 104 may determine the size of the PDCCH search space500 from information on the TDD frame structure received from the basestation 180. The UE 104 may determine a search strategy over the PDCCHsearch space 500 of 16 DL subframes. Given that the PDCCH search space500 has 16 DL subframes, the UE 104 may determine that a maximumaggregation level for the PDCCH search space 500 is 16. As mentioned,the number of CCEs in a PDCCH is called an aggregation level, and may be1, 2, 4, 8, or 16 consecutive CCEs at the first 1, 2, or 3 symbols of 1,2, 4, 8, or 16 consecutive subframes, respectively.

The UE 104 then performs a blind decoding or searching of the determinedPDCCH search space 500 to obtain control information for the UE 104. Inthis example, the UE 104 performs a blind decoding or searching over thedetermined PDCCH search space 500 based on the determined maximumaggregation level of 16. Thus, the determined PDCCH search space 500 of16 DL subframes has 1 PDCCH candidate at an aggregation level of 16(which is the maximum aggregation level for the PDCCH search space 500),has 2 PDCCH candidates at an aggregation level of 8, has 4 PDCCHcandidates at an aggregation level of 4, and 8 PDCCH candidates at anaggregation level of 2. The PDCCH candidates at an aggregation level ofn may only start on a boundary of every n subframes. Using standarddecoding techniques, the UE 104 performs PDCCH decoding of each of thesePDCCH candidates in the PDCCH search space 500 to obtain common and/orUE specific control information.

In another example and with regards to the TDD frame structure 400Bhaving the flexible section 406B, the base station 180 may indicate thatthe number of DL subframes in the set of frames for the PDCCH searchspace 502 is 8 DL subframes. As such, the UE 104 may receive informationfrom the base station 180 indicating the size of the PDCCH search space502. In one aspect, the UE 104 may determine the size of the PDCCHsearch space 502 from information on the TDD frame structure receivedfrom the base station 180. Thus, the UE 104 may determine a searchstrategy over the PDCCH search space 502 of 8 DL subframes. Given thatthe PDCCH search space 502 has 8 DL subframes, the UE 104 may determinethat a maximum aggregation level for the PDCCH search space 502 is 8.

The UE 104 then performs a blind decoding of the determined PDCCH searchspace 502 to obtain control information for the UE 104. In this example,the UE 104 performs a blind decoding over the determined PDCCH searchspace 502 based on the determined maximum aggregation level of 8. Thus,the determined PDCCH search space 502 of 8 DL subframes has 1 PDCCHcandidate at an aggregation level of 8 (which is the maximum aggregationlevel for the PDCCH search space 502), has 2 PDCCH candidates at anaggregation level of 4, and has 4 PDCCH candidates at an aggregationlevel of 2. Using standard decoding techniques, the PDCCH UE 104performs decoding of each of these PDCCH candidates in the PDCCH searchspace 502 to obtain common and/or UE specific control information.Analogous processes and techniques may be provided by the UE 104 and thebase station 180 with regards to the TDD frame structures 400C, 400Dwith the flexible sections 406C, 406D with PDCCH search spaces having anumber of DL subframes of 4 and 2, respectively.

Within the control information (which may be DCI of a common PDCCH or aUE specific PDCCH), the UE 104 may also determine the expected TDD framestructure of the next frame or set of frames in addition to the currentTDD frame structure. This TDD frame structure may be applicable even ifthe base station 180 does not transmit on the next frame due to LBTfailure. The UE 104 may use the control information about the currentand next TDD frame structure to determine resources for various physicalchannels, especially on the UL.

FIG. 6 illustrates a pair of PDCCH search spaces 600, 602 and arerelated to another technique for determining PDCCH candidates. The PDCCHsearch spaces 600, 602 are each provided by different TDD framestructures, such as the TDD frame structures 400A-400D shown in FIG. 4 .For example, the PDCCH search space 600 has a number of subframes whichmay contain PDCCH candidates. In this case, the PDCCH search space 600may be provided by the TDD frame structure 400B in FIG. 4 with theflexible portion 406B. In this case, the PDCCH search space 600 has atotal number of 16 subframes, which may be the first 16 DL subframes in,or may be distributed through, the set of frames in the TDD framestructure.

With regard to the PDCCH search space 602, the PDCCH search space 602has a greater number of subframes which may be provided with PDCCHcandidates than the maximum aggregation level of 16 for the PDCCH. Forexample, the PDCCH search space 602 may be provided by the TDD framestructure 400A in FIG. 4 with the flexible portion 406A. In this casethe PDCCH search space has a total number of 32 subframes, which may bethe first 32 DL subframes in, or may be distributed through, the set offrames in the TDD frame structure.

Each of the PDCCH search space 600, 602 is a function of the TDD framestructures. In particular, the size of the PDCCH search space and thenumber of PDCCH candidates may scale as a function of the number of DLsubframes in the TDD frame structure. As explained above with regards toFIG. 1 , the information from the base station 180 to the UE 104 mayindicate at least one of a location or a size of a PDCCH search spacewithin a set of subframes of a set of frames. The location and/or thesize of the PDCCH search space are a function of the TDD frame structureof the set of frames. In one aspect, the UE 104 may determine thelocation and/or the size of a PDCCH search size from information on theTDD frame structure received from the base station 180.

For example, with regards to the TDD frame structure 400B having theflexible section 406B, the base station 180 may indicate that the numberof DL subframes in the set of frames for the PDCCH search space is 16 DLsubframes. As such, the UE 104 may receive information from the basestation 180 indicating the size of the PDCCH search space. Theinformation indicating the size of a PDCCH search space 600 may be basedon a number of DL subframes in the set of frames. In one aspect, the UE104 may determine the size of the PDCCH search space 600 frominformation on the TDD frame structure received from the base station180. The UE 104 may determine a search strategy over the PDCCH searchspace 600 of 16 DL subframes. Given that the PDCCH search space 600 is16 DL subframes, the UE 104 may determine a search strategy to searchfor all PDCCH candidates at all possible aggregation level. In oneaspect, to keep the number of blind decoding constant as the size of thePDCCH search space increases, the UE may search a subset of all thePDCCH candidates of the determined PDCCH search space 600.

The UE 104 then performs a blind decoding of the determined PDCCH searchspace 600 to obtain control information for the UE 104. The UE 104 mayperform a blind decoding over the determined PDCCH search space 600based on all PDCCH candidates or a subset of the PDCCH candidates. Thus,the determined PDCCH search space 600 has 1 PDCCH candidate at anaggregation level of 16, has 2 PDCCH candidates at an aggregation levelof 8, has 4 PDCCH candidates at an aggregation level of 4, and 8 PDCCHcandidates at an aggregation level of 2. Using standard decodingtechniques, the UE 104 may perform PDCCH decoding of each of these PDCCHcandidates in the PDCCH search space 600 to obtain common and/or UEspecific control information.

In another example and with regards to the TDD frame structure 400Ahaving the flexible section 406A, the base station 180 may indicate thatthe number of DL subframes in the set of frames for the PDCCH searchspace is 32 DL subframes. As such, the UE 104 may receive informationfrom the base station 180 indicating the size of the PDCCH search space.The information indicating the size of a PDCCH search space 602 may bebased on a number of DL subframes in the set of frames, which in theexample for the PDCCH search space 602 is 32. In one aspect, the UE 104may determine the size of the PDCCH search space 602 from information onthe TDD frame structure received from the base station 180. The UE 104may determine a search strategy over the PDCCH search space 602 of 32 DLsubframes. In one aspect, the UE 104 may use information received fromthe base station 180 such as a cell radio network temporary identifier(C-RNTI) or a user identifier (UE-ID) when determining the searchstrategy. For example, to keep the number of blind decoding constant asthe size of the PDCCH search space increases, the UE may search a subsetof all the PDCCH candidates of the determined PDCCH search space 602 asa function of the C-RNTI, UE-ID, slot number, subframe number, framenumber, etc.

The UE 104 then performs a blind decoding of the determined PDCCH searchspace 602 to obtain control information for the UE 104. Given that thePDCCH search space 602 has 32 DL subframes, the UE 104 may perform ablind decoding of all possible PDCCH candidates over the determinedPDCCH search space 602. The maximum aggregation level for the PDCCH is16 and there are 2 PDCCH candidates over the PDCCH search space of 32 DLsubframes. For the aggregation level of 8, there are 4 PDCCH candidates.For the aggregation level of 4, there are 8 PDCCH candidates. For theaggregation level of 2, there are 16 PDCCH candidates. Using standarddecoding techniques, the UE 104 may perform PDCCH decoding of each ofthese PDCCH candidates in the PDCCH search space 602 to obtain commonand/or UE specific control information.

In one aspect, the UE 104 may perform a blind decoding of a subset ofthe possible PDCCH candidates, subject to a minimum at each aggregationlevel. The subset of the PDCCH candidates for blind decodes may bedetermined based on at least one of the C-RNTI or the user identifierUE-ID. Thus, the UE 104 may perform a blind decoding of only 16 of the32 DL subframes in the PDCCH search space 602 at each of the aggregationlevels of 16, 8, 4, 2. Which 16 of the 32 DL subframes to perform theblind decoding at each aggregation level may be determined based on atleast one of the C-RNTI, the user identifier UE-ID, slot number,subframe number, frame number or some other information about the UE 104or the frame structure.

For example, the UE 104 may perform the blind decoding over thedetermined PDCCH search space 602 at the maximum aggregation level of 16over the first 16 of the 32 DL subframes. Thus, 1 PDCCH candidate isdecoded at the aggregation level of 16. Additionally, the UE 104 mayperform the blind decoding over the determined PDCCH search space 602 atthe aggregation level of 8 over 16 of the 32 DL subframes. Thus, 2 PDCCHcandidates are decoded at the aggregation level of 8. Furthermore, theUE 104 may perform the blind decoding over the determined PDCCH searchspace 602 at the aggregation level of 4 over 16 of the 32 DL subframes.Thus, 4 PDCCH candidates are decoded at the aggregation level of 4.Finally, the UE 104 may perform the blind decoding over the determinedPDCCH search space 602 at the aggregation level of 2 over 16 of the 32DL subframes. Thus 8 PDCCH candidates are decoded at the aggregationlevel of 2. Using standard decoding techniques, the UE 104 may performPDCCH decoding of each of these PDCCH candidates in the PDCCH searchspace 602 to obtain common and/or UE specific control information.

Because the UE 104 may determine which of the 16 of the 32 subframes toperform blind decoding based on at least one of the C-RNTI, the useridentifier UE-ID, slot number, subframe number, frame number or someother information about the UE 104 or the frame structure, one largegrant of common and/or UE specific control information in the PDCCH doesnot block scheduling other UEs within the same frames. Also, UEmultiplexing is beneficial because for higher coverage enhancements, itis more efficient for the UE 104 to transmit on the UL on narrowband(e.g., 1RB or 2RB) and the rest of the RBs can be used to schedule otherUEs.

FIG. 7 illustrates a pair of TDD frame structures 700, 702. The TDDframe structures 700, 702 may be examples of the TDD frame structures400 shown in FIG. 4 . The TDD frame structure 700 has a number of ULsubframes which may be provided in the last frame and the second to lastframe of the set of frames. For example, the TDD frame structure 700 maybe an example of the TDD frame structure 400B in FIG. 4 with theflexible portion 406B. In this case, the TDD frame structure 700 has atotal number of 20 UL subframes.

With regard to the TDD frame structure 702, the TDD frame structure 702has a number of UL subframes which may be provided in the last frame ofthe set of frames. For example, the TDD frame structure 702 may be anexample of the TDD frame structure 400A in FIG. 4 with the flexibleportion 406A. In this case, the TDD frame structure 700 has a totalnumber of 10 UL subframes.

The UE 104 is configured to determine the TDD frame structure. Forexample, if the TDD frame structure is the TDD frame structure 700, thebase station 180 may transmit and the UE 104 may receive informationindicating the TDD frame structure 700. In one aspect, the UE 104 mayreceive information on the TDD frame structure through the PBCH, theMIB, or the SIB. In one case, the control information in the commonPDCCH or UE specific PDCCH for the UE 104 is used as the informationthat indicates the TDD frame structure 700. Similarly, if the TDD framestructure is the TDD frame structure 702, the base station 180 maytransmit and the UE 104 may receive information indicating the TDD framestructure 702.

Periodically, the base station 180 may assign physical resources (inparticular, physical uplink resources) which the UE 104 then uses totransmit uplink access, uplink control information, and other non-datainformation. For example, the UE 104 may be configured to determine alocation of at least one of a PRACH, PUCCH, SRS, SR resources based onthe determined TDD frame structure. The PRACH/PUCCH/SRS/SR resources ata certain repetition level may be semi-statically configured to occur ata fixed location in time or frequency. For example, the repetition levelfor the PRACH/PUCCH/SRS/SR resources in the TDD frame structure 700 is10 while the repetition level in the TDD frame structure 702 is 5. Inone aspect, the PRACH/PUCCH/SRS/SR resources may be configured to occureven when the base station 180 does not clear the medium. If thePRACH/PUCCH/SRS/SR resources are configured to occur on a UL subframeassigned for the PRACH/PUCCH/SRS/SR resources based on the informationon the frame structure, then the PRACH/PUCCH/SRS/SR resources areavailable for transmission over the assigned UL subframe. Otherwise, ifthe PRACH/PUCCH/SRS/SR resources are configured to occur on a DLsubframe or on a UL subframe not assigned for the PRACH/PUCCH/SRS/SRresources, then the PRACH/PUCCH/SRS/SR resources are not available.

In one aspect, the UE 104 may receive information indicating a change inthe TDD frame structure for a second set of frames that follow the setof frames. For example, the PRACH/PUCCH/SRS/SR resources may occur onlyat fixed subframe locations such as in the second to last frame in theTDD frame structure 700. However, if these subframe locations are not ULsubframes, like in the TDD frame structure 702, the PRACH/PUCCH/SRS/SRresources would not be available and would not be provided at all. Thus,if the first set of frames is provided with the TDD frame structure 700while a second set of frames is provided with the TDD frame structure702, the UE 104 may receive information from the base station 180indicating a change in the TDD frame structure from the TDD framestructure 700 for the first set of frames to the TDD frame structure 702for a second set of frames. In this case, the UE 104 would know that thePRACH/PUCCH/SRS/SR resources are not available in the second to lastframe within the TDD frame structure 702.

In one aspect, the PRACH and SR resources may be available dynamically,such as when the PRACH and SR resources are configured to occur at arepetition level, and may be usable by the UE 104 as they are notscheduled for use by the base station 180. In one aspect, theavailability of the PUCCH resources, such as ACK/NACK resources, used bythe UE 104 for the UL may be indicated in the DL grant. In one aspect,the availability of the resources for P-CSI transmission is dependent onthe availability of the PUCCH resources or PUSCH resources. If the PUCCHor PUSCH resources are available, the P-CSI is transmitted. Otherwise,the transmission of the P-CSI is dropped. In one aspect, with regards tothe measurements of the PRS received from the base station 180, thenumber of the subframes over which the PRS is transmitted may be staticor may be a function of the frame structure. The UE 104 may determinefrom the frame structure the number of subframes over which the PRS istransmitted. The UE 104 may measure the PRS over the determined numberof subframes and may transmit the measured PRS to the base station 180using the UL subframes.

Given that the UE 104 is configured to determine the TDD framestructure, the UE 104 may also use the TDD frame structure to determineresources available for making measurements relevant to the base station180. For example, the UE 104 may determine a number of subframes overwhich to measure and to average a channel quality based on thedetermined TDD frame structure. The UE 104 may then send a CQI measuredover the determined number of subframes and may transmit the CQI over anumber of UL subframes, such as using the PUCCH resources when they areavailable.

FIG. 8 illustrates a call flow 800 illustrating certain aspects of thedisclosure with respect to a UE 802 and a base station 804. At procedure806, the base station 804 transmits and the UE 802 may receiveinformation indicating at least one of a location or a size of a PDCCHsearch space within a set of subframes of a set of frames. The locationand/or the size of the PDCCH search space are a function of the TDDframe structure of the set of frames, as explained above with regards toFIG. 4-6 . In one aspect, the base station 804 may transmit and the UE802 may receive information indicating the TDD frame structure of theset of frames. For example, the information may indicate the number ofDL frames or the number of DL subframes in the set of frames. Theinformation may be broadcast in a physical DL channel, such as thephysical broadcast channel (PBCH), and be provided as information withina master information block (MIB) or a system information block (SIB).

At procedure 808, the UE 802 may determine the PDCCH search space withinthe set of subframes and a search strategy. The UE 802 determines thePDCCH search space based on the received information indicating the atleast one of the location or the size of the PDCCH search space, orbased on the received information indicating the structure of the TDDframes in the set of frames. For example, the base station 180 mayindicate the number of DL subframes in the set of frames for the PDCCHsearch space. In one aspect, the UE 802 may determine the number of DLsubframes from information on the TDD frame structure, and from thenumber of DL subframes, the UE 802 may determine the location and/orsize of the PDCCH search space. For the search strategy, the UE 802 maydetermine a maximum aggregation level for the PDCCH search space (e.g.,See FIG. 5 ) based on the number of DL subframes in the set of frames ofthe PDCCH search space. In one aspect, the UE 802 may determine a searchstrategy to search for all PDCCH candidates at all possible aggregationlevel. In one aspect, to keep the number of blind decoding constant asthe size of the PDCCH search space increases, the UE 802 may determine asearch strategy to search a subset of all the PDCCH candidates of thedetermined PDCCH search space at different aggregation levels, subjectto a minimum of blind decodes at each aggregation level (e.g., See FIG.6 ).

At procedure 810, the base station 804 transmits control information onPDCCHs, a C-RNTI or UE-ID for the UE 802, and a PRS to the UE 802. TheUE 802 then performs a blind decoding over the determined PDCCH searchspace to obtain control information for the UE 802, as shown inprocedure 812. The UE 802 may perform the blind decoding over thedetermined PDCCH search space 502 based on the determined maximumaggregation to search for all PDCCH candidates at all possibleaggregation level according to the search strategy (e.g., See FIG. 5 ).In one aspect, the UE 802 may search a subset of all the PDCCHcandidates of the determined PDCCH search space at different aggregationlevels according to the search strategy (e.g., See FIG. 6 ). In oneaspect, the subset of blind decodes may be determined based on at leastone of a C-RNTI, a user identifier UE-ID for the UE 802, slot number,subframe number, frame number or some other information about the UE 104or the frame structure, subject to a minimum of blind decodes at eachaggregation level.

Using standard decoding techniques, the UE 802 may perform PDCCHdecoding of each of these PDCCH candidates in the PDCCH search space toobtain common and/or UE specific control information. In one aspect,within the control information (which may be DCI of a common PDCCH or aUE specific PDCCH), the base station 804 can indicate the expected TDDframe structure of the next frame in addition to the current TDD framestructure. The UE 802 may use the control information about the currentand next TDD frame structure to determine resources for various physicalchannels, especially on the UL.

Accordingly, at procedure 814, the UE 802 determines a TDD framestructure, such as the assignment of the UL subframes. The UE 802 mayreceive information indicating the TDD frame structure, such as withinthe control information in the PDCCH (either common or UE specific). Inone aspect, the UE 104 may receive information on the TDD framestructure through the PBCH, the MIB, or the SIB. Periodically, the basestation 804 assigns physical resources (in particular, physical uplinkresources) which the UE 104 then uses to transmit uplink access, uplinkcontrol information, and other non-data information. At procedure 816,based on the determined TDD frame structure, the UE 802 determines alocation of at least one of a PRACH, a PUCCH, SRS, SR resources. Forexample, as explained in FIG. 7 , the PRACH/PUCCH/SRS/SR resources at acertain repetition level may be semi-statically configured to occur at afixed location in time or frequency. If the PRACH/PUCCH/SRS/SR resourcesare configured to occur on a UL subframe of the frame structure assignedfor the PRACH/PUCCH/SRS/SR resources, then the PRACH/PUCCH/SRS/SRresources are available for transmission over the assigned UL subframe.Otherwise, if the PRACH/PUCCH/SRS/SR resources are configured to occuron a DL subframe or on a UL subframe not assigned for thePRACH/PUCCH/SRS/SR resources, then the PRACH/PUCCH/SRS/SR resources arenot available for transmission.

In another example explained in FIG. 7 , the UE 802 may receiveinformation indicating a change in the TDD frame structure for a secondset of frames that follow the current set of frames. For example, thePRACH/PUCCH/SRS/SR resources may occur only at fixed subframe locations.Thus, if these subframe locations are UL subframes, thePRACH/PUCCH/SRS/SR resources are available. However, if these subframelocations are not UL subframes, the PRACH/PUCCH/SRS/SR resources wouldnot be available and would not be provided at all. Thus, the UE 802 mayreceive information from the base station 804 indicating a change in theTDD frame structure.

Given that the UE 802 is configured to determine the TDD framestructure, the UE 802 may also use the TDD frame structure to determineresources available for making measurements relevant to the base station804. For example, at procedure 818 the UE 802 may determine a number ofDL subframes over which to measure and to average a CQI based on thedetermined TDD frame structure. In one aspect, the UE 802 may determinea number of DL subframes over which the PRS is received from the basestation 804 based on the determined TDD frame structure for the UE 802to measure the PRS.

At procedure 820, the UE 802 may then transmit PRACH/PUCCH/SRS/SR/P-CSIusing the at least one of the PRACH, the PUCCH, the SRS, or the SRresources based on the determined location of the PRACH, the PUCCH, theSRS, or the SR resources. With regards to the PRS, the UE 802 may beconfigured to measure the PRS based on the determined number of DLsubframes containing the PRS, which was received at procedure 810. TheUE 802 may transmit the PRS measurement to the base station 804 usingone or more UL subframes, such as using the PUCCH resources when theyare available. In one aspect, the UE 802 is configured to measure and toaverage the CQI based on the determined number of DL subframes overwhich to make the CQI measurement. At procedure 822, the UE 802 sendsthe CQI to the base station 804. The UE 802 may transmit the CQI over anumber of UL subframes, such as using the PUCCH resources when they areavailable.

FIG. 9 is a flowchart 900 of a method of wireless communication. Themethod may be performed by a UE (e.g., 104, 802) to obtain controlinformation that are allocated in a flexible manner into subframes as afunction of a TDD frame structure. For example, the UE may determine aPDCCH search space and a search strategy from a TDD frame structure andmay perform a blind decoding of the PDCCH search space to obtaindownlink control information.

At 902, the UE receives, from a base station, information indicating aTDD frame structure of a set of frames. For example, the information mayindicate the number of DL frames or the number of DL subframes in theset of frames. In one aspect, the information may indicate at least oneof a location or a size of a PDCCH search space within a set ofsubframes in the set of frames. The location and/or the size of thePDCCH search space are a function of the TDD frame structure of the setof frames. The base station may broadcast the information in a physicalDL channel, such as the PBCH, and may provide the information within aMIB or a SIB.

At 904, the UE determines a physical downlink control channel PDCCHsearch space within a set of subframes in the set of frames based on thereceived information indicating the TDD frame structure. The PDCCHsearch space may indicate at least one of a location or a size of thePDCCH search space. The location or the size of the PDCCH search spaceis a function of a TDD frame structure of the set of frames. In oneaspect, the received information may indicate the number of DL subframesin the set of frames for the PDCCH search space. In one aspect, the UEmay determine the number of DL subframes from information on the TDDframe structure, and from the number of DL subframes, the UE maydetermine the location and/or size of the PDCCH search space.

At 906, the UE determines a search strategy including a maximumaggregation level based on the PDCCH search space. For example, the UEmay determine a search strategy based on the location and/or size of thePDCCH search space. In one aspect, the UE may determine a searchstrategy to search for all PDCCH candidates at all possible aggregationlevels based on the maximum aggregation level within the PDCCH searchspace. In one aspect, to keep the number of blind decoding constant asthe size of the PDCCH search space increases, the UE may determine asearch strategy to search a subset of all the PDCCH candidates of thePDCCH search space at different aggregation levels.

At 908, the UE performs a blind decoding of the determined PDCCH searchspace using the search strategy to obtain control information. In oneaspect, the UE may perform a blind decoding of all possible PDCCHcandidates at all possible aggregation levels based on a maximumaggregation level over the determined PDCCH search space. For example,if the PCCH search space is 32 DL subframes, the UE may search for all 2PDCCH candidates for the maximum aggregation level of 16, for all 4PDCCH candidates for the aggregation level of 8, for all 8 PDCCHcandidates for the aggregation level of 4, and for all 16 PDCCHcandidates for the aggregation level of 2. In one aspect, the UE mayperform a blind decoding of a subset of the possible PDCCH candidates,subject to a minimum at each aggregation level.

FIG. 10 is a flowchart 1000 of a method of wireless communication. Themethod may be performed by a UE (e.g., 104, 802) to determine aplurality of UL subframes that are allocated in a flexible manner as afunction of a TDD frame structure. The plurality of UL subframes may beassigned by the base station for transmitting UL resources associatedwith a number of control signaling. The UE may determine a location of ascheduled UL resource within the TDD frame structure for communicatingone of the number of the control signaling. The control signaling mayinclude PRACH, PUCCH, SRS, or SR.

At 1002, the UE determines a TDD frame structure. The UE may determinethe TDD frame structure, such as the assignment of the UL subframes,from the control information in the PDCCH (either common or UEspecific). The assignment of the UL subframes may dynamically change asa function of the TDD frame structure. In one aspect, the UE maydetermine the TDD frame structure through the PBCH, the MIB, or the SIB.The base station may periodically assign physical uplink resources whichthe UE may use to transmit uplink access, uplink control information,and other non-data information.

At 1004, the UE determines a location of at least one of a scheduledPRACH, a PUCCH, SRS, or SR resources. For example, the PRACH, PUCCH,SRS, or SR resources at a certain repetition level may besemi-statically configured to occur at a fixed location in time orfrequency. If the PRACH/PUCCH/SRS/SR resources are configured to occuron a UL subframe of the frame structure assigned for thePRACH/PUCCH/SRS/SR resources, then the PRACH/PUCCH/SRS/SR resources areavailable for transmission over the assigned UL subframe. Otherwise, ifthe PRACH/PUCCH/SRS/SR resources are configured to occur on a DLsubframe or on a UL subframe not assigned for the PRACH/PUCCH/SRS/SRresources, then the PRACH/PUCCH/SRS/SR resources are not available fortransmission.

At 1006, the UE determines if the scheduled PRACH, PUCCH, SRS, or SRresources are configured to occur on a UL subframe of the TDD framestructure assigned for the PRACH, PUCCH, SRS resources. For example, therepetition level for the PRACH/PUCCH/SRS/SR resources in the TDD framestructure may be 10 subframes. The UE determines if the repetition levelfor the PRACH/PUCCH/SRS/SR resources coincide with a UL subframeassigned for the PRACH/PUCCH/SRS/SR resources based on the framestructure.

At 1008, if the scheduled PRACH, PUCCH, SRS, or SR resources areconfigured to occur on a UL subframe of the TDD frame structure assignedfor the PRACH, PUCCH, SRS resources, the UE may transmit at least one ofthe PRACH, PUCCH, SRS, SR, or P-CSI using the scheduled PRACH, PUCCH,SRS, or SR resources over the assigned UL subframe. For example, thePRACH resource may occur only at fixed subframe locations. If one ofthese subframe locations coincides with a UL subframe assigned for thePRACH resource, the UE may transmit the PRACH resource over the ULsubframe.

Otherwise, at 1012, if the scheduled PRACH, PUCCH, SRS resources areconfigured to occur on a DL subframe or on a UL subframe not assignedfor the PRACH, PUCCH, SRS, or SR resources, then the UE does nottransmit the PRACH, PUCCH, SRS, SR, or P-CSI. For example, the PRACHresource may occur only at fixed subframe locations. If one of thesesubframe locations coincides with a DL subframe, or a UL subframe notassigned for the PRACH resource, then the UE does not transmit the PRACHresource.

In one aspect, at 1010, the UE determines a number of DL subframes overwhich to measure and to average a CQI based on the determined TDD framestructure. The UE may measure and average the CQI based on thedetermined number of DL subframes. In one aspect, at 1010, the UE maydetermine a number of DL subframes over which the PRS is received from abase station based on the determine TDD frame structure for the UE tomeasure the PRS. The UE may measure the PRS based on the determinednumber of DL subframes containing the PRS. At 1008, the UE sends the CQIor the PRS measurement using at least one of the scheduled PRACH, PUCCH,SRS, SR resources over one of the UL subframes assigned if the scheduledPRACH, PUCCH, SRS, or SR resources occur on a UL subframe of the TDDframe structure assigned for the PRACH, PUCCH, SRS resources. Forexample, The UE may transmit the CQI or the PRS measurement over anumber of UL subframes, such as using the PUCCH resources when they areavailable. If the scheduled PRACH, PUCCH, SRS resources are configuredto occur on a DL subframe or on a UL subframe not assigned for thePRACH, PUCCH, SRS, or SR resources, then the UE does not transmit theCQI or the PRS measurement.

FIG. 11 a conceptual data flow diagram illustrating the data flowbetween different modules/means/components in an exemplary apparatus1102. The apparatus 1102 may be a UE. The apparatus 1102 may include aTDD structure determination component 1126, a search space and searchstrategy determination component 1122, a blind decoding component 1124,a UL subframes for UL resources availability determination component1128, and a CQI/PRS measurement component, a UL resources transmissioncomponent 1130. The TDD structure determination component 1126 may beconfigured to receive, from a base station, via an antenna 1150,information about a time division duplex (TDD) frame structure of aplurality of frames and/or to determine the TDD frame structure. Forexample, the information may indicate the number of DL frames or thenumber of DL subframes in the set of frames. The TDD structuredetermination component 1126 may be configured to pass information onthe number of DL frames or the number of DL subframes to the searchspace and search strategy determination component 1122.

The search space and search strategy determination component 1122 may beconfigured to determine the PDCCH search space within the set of DLsubframes and to determine a search strategy. For example, from theinformation on the number of DL subframes of the TDD frame structurereceived from the TDD structure determination component 1126, thelocation and/or the size of the PDCCH search space may be determined.For the search strategy, a maximum aggregation level may be determined.The search strategy may determine whether to search all or a subset ofthe PDCCH candidates in the PDCCH search space based on the number of DLsubframes of the PDCCH search space. The search space and searchstrategy determination component 1122 may be configured to generateinformation on the PDCCH search space and the search strategy to theblind decoding component 1124. The blind decoding component 1124 may beconfigured to perform a blind decoding over the determined PDCCH searchspace to obtain control information for the apparatus 1102. For example,the blind decoding component 1124 may be configured to perform the blinddecoding over the PDCCH search space based on the determined maximumaggregation to search for all PDCCH candidates at all possibleaggregation level. In one aspect, the blind decoding component 1124 maybe configured to search a subset of all the PDCCH candidates of thePDCCH search space at different aggregation levels according to thesearch strategy. The blind decoding component 1124 may be configureddecode each of these PDCCH candidates in the PDCCH search space toobtain common and/or UE specific control information. The controlinformation in the PDCCH about the current TDD frame structure may beused by the apparatus 1102 to determine resources for UL.

The UL subframes for UL resources availability determination component1128 may be configured to receive the control information in the PDCCHfrom the search space and search strategy determination component 1122.The UL subframes for UL resources availability determination component1128 may also be configured to receive, from the TDD structuredetermination component 1126, information on UL physical resources thatmay be used to transmit uplink access, uplink control information,and/or other non-data information. The UL subframes for UL resourcesavailability determination component 1128 may be configured to determinea location of at least one of a PRACH, a PUCCH, SRS, SR resources. Ifthe PRACH/PUCCH/SRS/SR resources are configured to occur on a ULsubframe of the frame structure assigned for the PRACH/PUCCH/SRS/SRresources, then the PRACH/PUCCH/SRS/SR resources are available fortransmission over the assigned UL subframe. Otherwise, if thePRACH/PUCCH/SRS/SR resources are configured to occur on a DL subframe oron a UL subframe not assigned for the PRACH/PUCCH/SRS/SR resources, thenthe PRACH/PUCCH/SRS/SR resources are not available for transmission. TheUL subframes for UL resources availability determination component 1128may be configured to transmit PRACH/PUCCH/SRS/SR resources that areavailable for transmission to the UL resources transmission component1130.

The UL resources transmission component 1130 may be configured tocommunicate PRACH/PUCCH/SRS/SR using the scheduled UL resource over oneof the plurality of UL subframes when the location of the scheduled ULresource for communicating PRACH/PUCCH/SRS/SR occurs on one of theplurality of UL subframes assigned for transmitting the scheduled ULresource, as determined by the UL subframes for UL resourcesavailability determination component 1128. The UL resources transmissioncomponent 1130 may be configured to communicate the PRACH/PUCCH/SRS/SRto the antenna 1150 for UL transmission to the base station.

The CQI/PRS measurement component 1132 may be configured to determine anumber of DL subframes over which to measure and to average a CQI basedon the TDD frame structure received from the TDD structure determinationcomponent 1126. The CQI/PRS measurement component 1132 may be configuredto measure and to average the CQI based on the determined number of DLsubframes. In one aspect, the CQI/PRS measurement component 1132 may beconfigured to determine a number of DL subframes over which the PRS isreceived from a base station based on the TDD frame structure for theapparatus 1102 to measure the PRS. The CQI/PRS measurement component1132 may be configured to measure the PRS based on the number of DLsubframes containing the PRS. The CQI/PRS measurement component 1132 maybe configured to send the CQI or the PRS measurement to the UL resourcestransmission component 1130. The UL resources transmission component1130 may be configured to use at least one of the scheduled PRACH,PUCCH, SRS, SR resources over one of the UL subframes to communicate theCQI or the PRS measurement, such as using the PUCCH resources when theyare available. The UL resources transmission component 1130 may beconfigured to communicate the CQI or the PRS measurement to the antenna1150 for UL transmission to the base station.

FIG. 12 is a diagram 1200 illustrating an example of a hardwareimplementation for an apparatus 1202′ employing a processing system1214. The processing system 1214 may be implemented with a busarchitecture, represented generally by the bus 1208. The bus 1208 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1214 and the overalldesign constraints. The bus 1208 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 1204, the components 1122, 1124, 1126, 1128, 1130,1132, and the computer-readable medium/memory 1206. The bus 1208 mayalso link various other circuits such as timing sources, peripherals,voltage regulators, and power management circuits, which are well knownin the art, and therefore, will not be described any further.

The processing system 1214 may be coupled to a transceiver 1210. Thetransceiver 1210 is coupled to one or more antennas 1220. Thetransceiver 1210 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1210 receives asignal from the one or more antennas 1220, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1214, specifically the blind decoding component 1124.In addition, the transceiver 1210 receives information from theprocessing system 1214, specifically the UL resources transmissioncomponent 1130, and based on the received information, generates asignal to be applied to the one or more antennas 1220. The processingsystem 1214 includes a processor 1204 coupled to a computer-readablemedium/memory 1206. The processor 1204 is responsible for generalprocessing, including the execution of software stored on thecomputer-readable medium/memory 1206. The software, when executed by theprocessor 1204, causes the processing system 1214 to perform the variousfunctions described supra for any particular apparatus. Thecomputer-readable medium/memory 1206 may also be used for storing datathat is manipulated by the processor 1204 when executing software. Theprocessing system further includes at least one of the components 1122,1124, 1126, 1128, 1130, and 1132. The components may be softwarecomponents running in the processor 1204, resident/stored in thecomputer readable medium/memory 1206, one or more hardware componentscoupled to the processor 1204, or some combination thereof.

In one configuration, the apparatus 1202′ may include means forreceiving, from a base station, information about a time division duplex(TDD) frame structure of a plurality of frames and/or means fordetermining the TDD frame structure. The means to receive informationabout the TDD frame structure and/or means to determine the TDD framestructure may be implemented by the TDD structure determinationcomponent 1126. The plurality of frames includes a plurality ofsubframes. A plurality of UL subframes of the plurality of framesassigned for transmitting a plurality of UL resources associated with acontrol signaling is a function of the TDD frame structure. Theapparatus 1202′ may include means for determining a control channelsearch space within the plurality of subframes based on the informationabout the TDD frame structure of the plurality of frames. The apparatus1202′ may include means for determining a search strategy based on thecontrol channel search space. The means for determining the controlchannel search space and the search strategy may be implemented by thesearch space and search strategy determination component 1122. Theapparatus 1202′ may include means for performing a blind decoding of thecontrol channel search space with the search strategy to obtain controlinformation. The means for the blind decoding may be implemented by theblind decoding component 1124.

In one configuration, the apparatus 1202′ may include means fordetermining a location of a scheduled UL resource within the TDD framestructure for communicating a type of control signaling. The controlsignaling may include a random access channel, a uplink control channel,a SRS, or a SR. The apparatus 1202′ may include means for determining ifthe location of the scheduled UL resource for communicating a type ofthe control signaling occurs on one of the plurality of UL subframesassigned for transmitting the scheduled UL resource. The means fordetermining the availability of the UL subframes for the scheduled ULresources for communicating the control signaling associated with thescheduled UL resources may be implemented by the UL subframes for ULresources availability determination component 1128. The apparatus 1202′may include means for communicating a type of the control signalingusing the scheduled UL resource over one of the plurality of ULsubframes when the location of the scheduled UL resource forcommunicating the type of the control signaling occurs on one of theplurality of UL subframes assigned for transmitting the scheduled ULresource. The means for communicating the control signaling may beimplemented by the UL resources transmission component 1130. Theapparatus 1202′ may include means for determining a number of DLsubframes of the plurality of frames over which to measure a CQI or aPRS based on the TDD frame structure and means for measuring the CQI orthe PRS over the determined number of DL subframes. The means for theCQI/PRS measurement may be implemented by the CQI/PRS measurementcomponent 1132. Any of the aforementioned means may be one or more ofthe processing system 1214 of the apparatus 1202′ configured to performthe functions recited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the processes/flowcharts may berearranged. Further, some blocks may be combined or omitted. Theaccompanying method claims present elements of the various blocks in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed as a means plus function unless the elementis expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication of a userequipment (UE), comprising: receiving a configuration of a time divisionduplex (TDD) frame structure for a plurality of frames, wherein theplurality of frames include a plurality of uplink (UL) periods and aplurality of downlink (DL) periods; transmitting a periodic controlsignaling instance if the periodic control signaling instance isscheduled during the UL periods of the TDD frame structure, wherein theperiodic control signaling instance is scheduled periodically and theperiodic control signaling includes at least one of a random accesschannel, an uplink control channel, a sounding reference signal (SRS),or a scheduling request (SR); measuring at least one of a channelquality indicator (CQI) or a positioning reference signal (PRS) using DLsubframes, wherein CQI or PRS measurements are not transmitted inresponse to an UL subframe unassigned to periodic control signalingresources; and skipping transmission of the periodic control signalinginstance in response to the periodic control signaling instance beingscheduled to occur during a DL period, wherein the periodic controlsigning resources are unavailable.
 2. The method of claim 1, wherein thetransmitting of the periodic control signaling instance comprisestransmitting at least one of the random access channel, the uplinkcontrol channel, the SRS, or the SR on one of the plurality of ULperiods assigned for transmitting an UL resource.
 3. The method of claim1, further comprising transmitting a periodic channel state information(P-CSI) on one of the plurality of UL periods assigned for transmittingan UL resource associated with the at least one of the random accesschannel, the uplink control channel, the SRS, or the SR.
 4. The methodof claim 1, further comprising: determining a number of DL periods ofthe plurality of frames over which to average for a channel qualitymeasurement based on the TDD frame structure; measuring and averagingthe CQI over the determined number of DL periods; and transmitting theCQI on one of the plurality of UL periods assigned for transmitting anUL resource associated with the at least one of the random accesschannel, the uplink control channel, the SRS, or the SR.
 5. The methodof claim 1, further comprising: determining a number of DL periods ofthe plurality of frames over which to measure the PRS based on the TDDframe structure; measuring the PRS over the determined number of DLperiods to generate a PRS measurement; and transmitting the PRSmeasurement on one of the plurality of UL periods assigned fortransmitting an UL resource associated with the at least one of therandom access channel, the uplink control channel, the SRS, or the SR.6. The method of claim 1, further comprising receiving informationindicating a change in the TDD frame structure for a second set offrames that follow the plurality of frames.
 7. An apparatus for wirelesscommunication, comprising: a processing system, configured to: receive aconfiguration of a time division duplex (TDD) frame structure for aplurality of frames, wherein the plurality of frames include a pluralityof uplink (UL) periods and a plurality of downlink (DL) periods;transmit a periodic control signaling instance if the periodic controlsignaling instance is scheduled during the UL periods of the TDD framestructure, wherein the periodic control signaling instance is scheduledperiodically and the periodic control signaling includes at least one ofa random access channel, an uplink control channel, a sounding referencesignal (SRS), or a scheduling request (SR); measure at least one of achannel quality indicator (CQI) or a positioning reference signal (PRS)using DL subframes, wherein CQI or PRS measurements are not transmittedin response to an UL subframe unassigned to periodic control signalingresources; and skip transmission of the periodic control signalinginstance in response to the periodic control signaling instance beingscheduled to occur during a DL period, wherein the periodic controlsignaling resources are unavailable.
 8. The apparatus of claim 7,wherein the processing system is configured to transmit the periodiccontrol signaling instance by being configured to transmit at least oneof the random access channel, the uplink control channel, the SRS, orthe SR on one of the plurality of UL periods assigned for transmittingan UL resource.
 9. The apparatus of claim 7, wherein the processingsystem is further configured to transmit a periodic channel stateinformation (P-CSI) on one of the plurality of UL periods assigned fortransmitting an UL resource associated with the at least one of therandom access channel, the uplink control channel, the SRS, or the SR.10. The apparatus of claim 7, wherein the processing system is furtherconfigured to: determine a number of DL periods of the plurality offrames over which to average for a channel quality measurement based onthe TDD frame structure; measure and average the CQI over the determinednumber of DL periods; and transmit the CQI on one of the plurality of ULperiods assigned for transmitting an UL resource associated with the atleast one of the random access channel, the uplink control channel, theSRS, or the SR.
 11. The apparatus of claim 7, wherein the processingsystem is further configured to: determine a number of DL periods of theplurality of frames over which to measure the PRS based on the TDD framestructure; measure the PRS over the determined number of DL periods togenerate a PRS measurement; and transmit the PRS measurement on one ofthe plurality of UL periods assigned for transmitting an UL resourceassociated with the at least one of the random access channel, theuplink control channel, the SRS, or the SR.
 12. The apparatus of claim7, wherein the processing system is further configured to receiveinformation indicating a change in the TDD frame structure for a secondset of frames that follow the plurality of frames.
 13. An apparatus forwireless communication, comprising: means for receiving a configurationof a time division duplex (TDD) frame structure for a plurality offrames, wherein the plurality of frames include a plurality of uplink(UL) periods and a plurality of downlink (DL) periods; means fortransmitting a periodic control signaling instance if the periodiccontrol signaling instance is scheduled during the UL periods of the TDDframe structure, wherein the periodic control signaling instance isscheduled periodically and the periodic control signaling includes atleast one of a random access channel, an uplink control channel, asounding reference signal (SRS), or a scheduling request (SR); means formeasuring at least one of a channel quality indicator (CQI) or apositioning reference signal (PRS) using DL subframes, wherein CQI orPRS measurements are not transmitted in response to an UL subframeunassigned to periodic control signaling resources; and means forskipping transmission of the periodic control signaling instance inresponse to the periodic control signaling instance being scheduled tooccur during a DL period, wherein the periodic control signalingresources are unavailable.
 14. The apparatus of claim 13, wherein themeans for transmitting the periodic control signaling instance isfurther configured to transmit at least one of the random accesschannel, the uplink control channel, the SRS, or the SR on one of theplurality of UL periods assigned for transmitting an UL resource. 15.The apparatus of claim 13, wherein the means for transmitting theperiodic control signaling is further configured to transmit a periodicchannel state information (P-CSI) on one of the plurality of UL periodsassigned for transmitting an UL resource associated with the at leastone of the random access channel, the uplink control channel, the SRS,or the SR.
 16. The apparatus of claim 13, wherein the means fordetermining the TDD frame structure of the plurality of frames isfurther configured to determine a number of DL periods of the pluralityof frames over which to average for a channel quality measurement basedon the TDD frame structure, wherein the apparatus further comprisesmeans for measuring and averaging the CQI over the determined number ofDL periods, and wherein the means for communicating the periodic controlsignaling is further configured to transmit the CQI on one of theplurality of UL periods assigned for transmitting an UL resourceassociated with the at least one of the random access channel, theuplink control channel, the SRS, or the SR.
 17. The apparatus of claim13, wherein the means for determining the TDD frame structure of theplurality of frames is further configured to determine a number of DLperiods of the plurality of frames over which to measure the PRS basedon the TDD frame structure, wherein the apparatus further comprisesmeans for measuring the PRS over the determined number of DL periods togenerate a PRS measurement, and wherein the means for communicating theperiodic control signaling is further configured to transmit the PRSmeasurement on one of the plurality of UL periods assigned fortransmitting an UL resource associated with the at least one of therandom access channel, the uplink control channel, the SRS, or the SR.18. The apparatus of claim 13, wherein the means for determining the TDDframe structure of the plurality of frames is further configured toreceive information indicating a change in the TDD frame structure for asecond set of frames that follow the plurality of frames.
 19. Anon-transitory computer-readable medium storing computer executablecode, the code, when executed by a processor, to cause the processor to:receive a configuration of a time division duplex (TDD) frame structurefor a plurality of frames, wherein the plurality of frames include aplurality of uplink (UL) subframes and a plurality of downlink (DL)subframes; transmit a periodic control signaling instance if theperiodic control signaling instance is scheduled during the UL periodsof the TDD frame structure, wherein the periodic control signalinginstance is scheduled periodically and the periodic control signalingincludes at least one of a random access channel, an uplink controlchannel, a sounding reference signal (SRS), or a scheduling request(SR); measure at least one of a channel quality indicator (CQI) or apositioning reference signal (PRS) using DL subframes, wherein CQI orPRS measurements are not transmitted in response to an UL subframeunassigned to periodic control signaling resources; and skiptransmission of the periodic control signaling instance in response tothe periodic control signaling instance being scheduled to occur duringa DL period, wherein the periodic control signaling resources areunavailable.